Wouldn't rules like that require qualifying runs etc? I have no track experience, I guess I just assumed everyone would need a helmet. Allan already has his, and I'm pretty sure he's mostly stock as well...

I'm all stock. But it's required for the Pfadt track attack. So, I just got the cheapest one I could get. It just depends on what you are doing. You might not need one for the 1/4 mile.